Clothes dryers are mainly used to dry clothes by removing moisture from clothes that have just been washed.
The clothes dryers can be classified into an exhaust type and a condensation type according to a processing method of moist air generated while drying laundry. The former type employs a method of exhausting moist air from a dryer, while the latter employs a method of removing moisture by condensing moist air exhausted from a dryer and circulating the moisture-removed air again in the dryer.
Typically, in the exhaust type dryer, an air intake duct and an air exhaust duct are connected to a rotatable drum disposed inside a cabinet, the air intake duct having a heater disposed therein.
As air outside the dryer is introduced into the air intake duct by driving a fan, the air is heated to a high temperature by a heater. The heating temperature reaches up to about 100° C. This high temperature air is introduced into a drying drum in the dryer, thus drying laundry in the drum. In the drying procedure, the high temperature air gets to contain the moisture included in the laundry, and high humidity air is discharged through the air exhaust duct. Although such a conventional clothes dryer that delivers heat to an introduced air by using a heater has a merit that the overall drying time is shortened by the heater's rapid heating of air and it can be manufactured to have a large capacity, it has a drawback that the energy consumption is large because an introduced air is heated by the heater. Especially, there is a great probability that damages may occur depending on the material of laundry in the drying procedure since the laundry is dried with air of high temperature of 100° C. or higher.
Meanwhile, the condensation type clothes dryer has a merit that it can be manufactured in a built-in type since it requires no air exhaust duct for discharging air out of the clothes dryer, while it has a drawback that it requires a long drying time and is difficult to be manufactured to have a large capacity although its energy efficiency is higher than the exhaust type. Under this background, there is a demand for a clothes dryer that provides a high energy efficiency and is so improved that it may not cause a damage to laundry.
Meanwhile, in areas with a high humidity, for example, near seashores or areas with a long rain season, there is a problem in that the drying efficiency is relatively lower when the clothes dryer is used. This is because a large amount of moisture is contained in the air used to dry laundry. It requires a lot of time to dry laundry since the air containing a large amount of moisture is introduced into the drying drum with the moisture not being removed enough even if the air is increased in temperature by the heater, resultantly increasing the energy consumption required to complete the drying. Subsequently, there is a demand for a clothes dryer for supplying air to a drying drum with moisture removed enough from an introduced air.